DApp实战:开发属于你的第一个DApp

效果预览

项目的视频教程部分已经发布到了b站

https://space.bilibili.com/391924926/channel/seriesdetail?sid=2745034

初始化状态

添加

删除

开发环境准备

系统环境

Remix
Ganache
nodejs最新版
metamask

开发框架

vue-cli脚手架
web3.js
element-ui

vue-cli脚手架创建工程

vue create my-node

Vue CLI v5.0.1
┌─────────────────────────────────────────────┐
│                                             │
│     New version available 5.0.1 → 5.0.8     │
│   Run yarn global add @vue/cli to update!   │
│                                             │
└─────────────────────────────────────────────┘? Please pick a preset: Default ([Vue 2] babel, eslint)Vue CLI v5.0.1
✨  Creating project in /Users/sleep/Desktop/my-node.
��  Initializing git repository...
⚙️  Installing CLI plugins. This might take a while...yarn install v1.22.17
info No lockfile found.
[1/4] ��  Resolving packages...
[2/4] ��  Fetching packages...
[3/4] ��  Linking dependencies...success Saved lockfile.
info To upgrade, run the following command:
$ curl --compressed -o- -L https://yarnpkg.com/install.sh | bash
✨  Done in 14.18s.
��  Invoking generators...
��  Installing additional dependencies...yarn install v1.22.17
[1/4] ��  Resolving packages...
[2/4] ��  Fetching packages...
[3/4] ��  Linking dependencies...
[4/4] ��  Building fresh packages...success Saved lockfile.
✨  Done in 4.74s.
⚓  Running completion hooks...��  Generating README.md...��  Successfully created project my-node.
��  Get started with the following commands:$ cd my-node
$ yarn serve

安装依赖库

npm 安装 elementUI,web3js

npm i element-ui web3 -S

Solidity编写智能合约

注意点:

删除数组的练习, 我们发现数组元素不会真正删除只会置为0值

1,2,3,5 => 1,2,0,5

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;contract Array {uint256[] public arr=[1,2,3,4];constructor() {arr[0] = 1;arr[1] = 2;arr[2] = 3;arr[3] = 5;}function addArr(uint _x) public {arr.push(_x);}function deleteArr(uint256 i) public {delete arr[i];}function getArr() public view returns (uint256[] memory) {return arr;}
}

数组无法直接将某个元素删除,只能从后向前逐个删除。基于这个特性，我需要通过把把元素从右往左移动从而删除元素保留元素的顺序

// [1, 2, 3] -- remove(1) --> [1, 3, 3] --> [1, 3]
// [1, 2, 3, 4, 5, 6] -- remove(2) --> [1, 2, 4, 5, 6, 6] --> [1, 2, 4, 5, 6]
// [1, 2, 3, 4, 5, 6] -- remove(0) --> [2, 3, 4, 5, 6, 6] --> [2, 3, 4, 5, 6]
function remove(uint _index) public {require(_index < arr.length, "index out of bound");for (uint i = _index; i < arr.length - 1; i++) {arr[i] = arr[i + 1];}arr.pop();//交换后再把最后一个元素移除
}

我们也可以把最后一个元素copy 到被移动元素的位置从而达到移除元素。无序。

function remove(uint index) public {arr[index] = arr[arr.length - 1];arr.pop();//删除最后一个元素
}

最终合约代码

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;contract Note {// 定义日记本数据结构struct node {string name;string content;string date;}//定义每个用户自己的日记本列表存储对象mapping(address => node[]) public userNodeList;//添加成功的通知event addSuccess(address);//删除成功的通知event deleteSuccess(address);//获取当前用户的日记列表function getUserNodeList() external view returns (node[] memory) {return userNodeList[msg.sender];}//添加一条日记function addNode(string memory _name,string memory _content,string memory _date) external {userNodeList[msg.sender].push(node({name: _name, content: _content, date: _date}));emit addSuccess(msg.sender);}//删除一条日记function deleteNode(uint256 _x) external {require(userNodeList[msg.sender].length > _x, "out of index");for (uint256 i = _x; i < userNodeList[msg.sender].length - 1; i++) {userNodeList[msg.sender][i] = userNodeList[msg.sender][i + 1];}userNodeList[msg.sender].pop();emit deleteSuccess(msg.sender);}
}

编写前端界面样式

在 main.js 中写入以下内容：

import Vue from 'vue'
import App from './App.vue'
Vue.config.productionTip = false//先导入elementUI库
import ElementUI from 'element-ui';
import 'element-ui/lib/theme-chalk/index.css';
Vue.use(ElementUI);new Vue({render: h => h(App),
}).$mount('#app')

把前端的html结构搭建出来

<template><div id="app"><el-button type="primary" size="mini" @click="addNode">添加</el-button><el-table:data="tableData"style="width: 100%; "><el-table-columnprop="date"label="日期"width="180"></el-table-column><el-table-columnprop="name"label="标题"width="180"></el-table-column><el-table-columnprop="content"label="内容"><template v-slot="scope"><el-button @click="getContent(scope.row.content)">查看</el-button></template></el-table-column><el-table-column><template v-slot="scope"><el-button @click="deleteNode(scope.$index)" size="mini">删除</el-button></template></el-table-column></el-table><el-dialog :visible.sync="open"><el-form ref="form" :model="form" label-width="80px"><el-form-item label="标题"><el-input type="text" v-model="form.name"/></el-form-item><el-form-item label="内容"><el-input type="textarea" v-model="form.name"/></el-form-item><el-form-item label="时间"><el-date-picker v-model="form.date" type="datetime" placeholder="请输入时间"/></el-form-item></el-form><div slot="footer" class="dialog-footer"><el-button @click="open = false">取 消</el-button><el-button type="primary" @click="open = false">确 定</el-button></div></el-dialog><el-dialog :visible.sync="contentOpen"><div>{{ form.content }}</div></el-dialog></div>
</template><script>export default {name: 'App',components: {},data() {return {tableData: [{date: '2016-05-02',name: '王小虎',content: '上海市普陀区金沙江路 1518 弄'}],form: {name: "",content: "",date: "",},open: false,contentOpen: false}},methods: {addNode() {this.open = true},async deleteNode(index) {console.log(index)try {let res = await this.$confirm("确定要删除吗?");if (!res) {this.$message.error("删除失败")}//todo 调用删除合约方法} catch (e) {console.log(e)}},getContent(content) {this.contentOpen = truethis.form.content = content}}
}
</script>

准备区块链环境

Ganache

官网：https://trufflesuite.com/docs/ganache/

Ganache 是一个用与本地开发的区块链，用于在Ethereum区块链上开发去中心化的应用程序。Ganache 模拟了Ethereum网络，你可以在发布到生产环境之前看到你的 DApp 将如何执行。

Ganache 有两种形式：UI 和 CLI。

1.下载Ganache https://trufflesuite.com/ganache/，选择适合您操作系统的版本和安装文件

2。按照提示进行安装。

3。启动应用

首次打开会看到这样的界面

4.启动节点

点击quickstart按钮启动一个ETH节点
创建工作区后，屏幕将显示有关服务器的一些详细信息，并列出一些帐户。每个账户自带100ETH 。这种模式启动，数据只保存在内存中，关闭重新打开数据会重新初始化。另请注意，您可以从顶部的搜索框中搜索区块编号或交易哈希。
点击 New workspace 创建一个新的工作区
需要预先配置参数
定义工作区的名称和描述
定义服务相关参数配置
可以配置每个地址默认分配的ETH数量和账户总数等信息
配置好以后点击 save workspace完成最终配置。数据会保存到本地磁盘中，下次再启动应用还会重新加载数据。

web3.js调用合约

初始化web3js

import Web3 from 'web3';const web3 = new Web3(window.ethereum)
console.log(web3.version)

实例化合约

const contract = new web3.eth.Contract([abi], "合约地址");

调用合约方法

contract.methods.方法名(参数)//读取类的用 call.call({from: account})//写入类的用 send.send({from: account})

合约事件监听

myContract.events.event({filter: {},fromBlock: 'latest'}).on("connected", (subscriptionId) => {console.log("connected", subscriptionId);}).on('data', event => {console.log('data',event);//可以在这里写逻辑,比如刷新列表this.getUserNodeList(event.returnValues[0])}).on('changed', event => {// 从本地数据库中删除事件console.log('changed', event)}).on('error', (error, receipt) => {// 如果交易被网络拒绝并带有交易收据，第二个参数将是交易收据。console.log(error, receipt)});

最终代码

<template><div id="app"><div v-if="!view"> {{ tips }}</div><div v-else><el-button type="primary" size="mini" @click="addNode">添加</el-button><el-table:data="tableData"style="width: 100%; "><el-table-columnprop="date"label="日期"width="180"></el-table-column><el-table-columnprop="name"label="标题"width="180"></el-table-column><el-table-columnprop="content"label="内容"><template v-slot="scope"><el-button @click="getContent(scope.row.content)">查看</el-button></template></el-table-column><el-table-column><template v-slot="scope"><el-button @click="deleteNode(scope.$index)" size="mini">删除</el-button></template></el-table-column></el-table><el-dialog :visible.sync="open"><el-form ref="form" :model="form" label-width="80px"><el-form-item label="标题"><el-input type="text" v-model="form.name"/></el-form-item><el-form-item label="内容"><el-input type="textarea" v-model="form.content"/></el-form-item><el-form-item label="时间"><el-date-picker v-model="form.date" type="datetime" placeholder="请输入时间"/></el-form-item></el-form><div slot="footer" class="dialog-footer"><el-button @click="open = false">取 消</el-button><el-button type="primary" @click="saveNode">确 定</el-button></div></el-dialog><el-dialog :visible.sync="contentOpen"><div>{{ form.content }}</div></el-dialog></div></div>
</template><script>
import Web3 from "web3";export default {name: 'App',components: {},data() {return {tableData: [{date: '2016-05-02',name: '王小虎',content: '上海市普陀区金沙江路 1518 弄'}],form: {name: "",content: "",date: "",},open: false,contentOpen: false,view: false,tips: "",web3: null,contract: null,//部署合约后填写正确的合约地址contractAddress: "0x........",abi: [//....从json获取],accounts: []}},async mounted() {this.view = this.checkWallet()this.checkNetwork(0)await this.eventChange('connect')await this.eventChange('accountsChanged')await this.eventChange('chainChanged')this.accounts = await this.enableAccounts()console.log(this.accounts[0])this.web3 = await this.initWeb3js();this.contract = new this.web3.eth.Contract(this.abi, this.contractAddress);this.watchEvents(this.contract.events.addSuccess);this.watchEvents(this.contract.events.deleteSuccess);console.log(this.contract.methods)await this.getUserNodeList(this.accounts[0])},methods: {addNode() {this.open = true},async deleteNode(index) {console.log(index)try {let res = await this.$confirm("确定要删除吗?");if (!res) {this.$message.error("删除失败")}//todo 调用删除合约方法try {let res = await this.contract.methods.deleteNode(index).send({from: this.accounts[0]})console.log(res)await this.getUserNodeList(this.accounts[0])} catch (e) {this.$message.error(e)}} catch (e) {console.log(e)}},getContent(content) {this.contentOpen = truethis.form.content = content},/*web3js 相关方法*/async checkWallet() {if (typeof window.ethereum === 'undefined') {this.tips = "请安装钱包插件";return false;}return true;},checkNetwork(networkId) {if (!window.ethereum.isConnected()) {console.log('connect error!', networkId);this.view = false;this.tips = "请配置钱包链接地址";return false;}this.view = true;return true},async eventChange(event) {try {window.ethereum.on(event, async (data) => {console.log(data)switch (event) {case "connect":console.log(data)this.checkNetwork(data)break;case "networkChanged":this.checkNetwork(data)break;case 'accountsChanged':console.log(data)//这里注意一定要重新复制accountthis.accounts = data;await this.getUserNodeList(data[0]);break}})} catch (e) {this.$message.error(e)}},initWeb3js() {return new Web3(window.ethereum)},async enableAccounts() {try {return await window.ethereum.request({method: 'eth_requestAccounts'});} catch (e) {this.$message.error(e)}},watchEvents(event) {event({filter: {},fromBlock: 'latest'}).on("connected", (subscriptionId) => {//当订阅成功连接时触发一次。返回订阅 id。console.log("connected", subscriptionId);}).on('data', event => {console.log('data',event);//可以在这里写逻辑,比如刷新列表this.getUserNodeList(event.returnValues[0])}).on('changed', event => {//当事件从区块链上移除时触发。 // 从本地数据库中删除事件console.log('changed', event)}).on('error', (error, receipt) => {//当订阅中出现错误时触发。// 如果交易被网络拒绝并带有交易收据，第二个参数将是交易收据。console.log(error, receipt)});},/*合约函数*/async getUserNodeList(account) {this.tableData = await this.contract.methods.getUserNodeList().call({from: account})},async saveNode() {let {name, content, date} = this.formconsole.log(this.form)try {let res = await this.contract.methods.addNode(name, content, date.toString()).send({from: this.accounts[0]})console.log(res)this.open = falsethis.form = {}await this.getUserNodeList(this.accounts[0])} catch (e) {this.$message.error(e)}},}
}
</script>